The long-range interest underlying this proposal is the area of cellular interaction: how cells recognize and communicate with one another. The proposed project is the continued development of a tissue culture system for the investigation of neurospecificity. The first phase of this project has centered on establishment of techniques and conditions for isolation and growth of sympathetic neurons in culture. Currently we are investigating the basic electrophysiological, biochemical and morphological properties of the neurons grown in the absence of other cell types. The biochemical studies carried out this far have shown that this neuronal culture system may also be very useful in obtaining information about certain aspects of neuronal development, neurotransmitter metabolism, and synapse formation not easily studied in vivo.